Hey guys so I just bought a project 510 this past Tuesday and I am starting with trying to get it running. The PO pulled the motor to paint the engine bay and put the motor back in and said he had it running.

It's a stock 1.6, and the battery is good but when I go to start it nothing happens. The starter doesn't make a sound. The wiring harness looks to be a bit of a rats nest so I am assuming its a wiring issue. I started tracing back the ignition wire off the starter which led me to start unwrapping off all the tape and wrap off the harness but I thought I should stop and ask for advice here before I open a can of worms.

Any advice on where to start looking? I have printed out legible color versions of all the 510 schematics I can find but I haven't done much wiring in my days and of all aspects of working on a car wiring intimidates me the most.

510 wiring is about as simple as it gets. Between that and the color wiring diagram, it shouldn't be a big deal to fix. Which isn't to say simple or easy, just not impossible.

For Datsun wiring primers, check out:

DQ Volume 5 Issue 3 - Tech How-To: Troubleshooting Electrical Systems: Part One - Automotive electrical system fault diagnosis may be the most feared work for the backyard mechanic. Many people view electrical systems as a sort of black magic, best left to professional shops. This may hold true for newer computer controlled vehicles that rely on special diagnostic tools. This is definitely not true for older cars like our 510s that don’t utilize computers.

and

DQ Volume 6 Issue 1 - Troubleshooting Electrical Systems: Part Two - In part one we explored some basic electrical circuit types, general components, and a simple test case. In part two we’ll dig deeper into the different electrical components along with their specific purpose.

To your specific problems, there could be many. I'd start with jumping the starter across the two terminals. If that doesn't work, either the starter is dead, the battery is dead, or the cables have major problems. Once you've verified those three things work (by way of the starter turning the engine over), we can go from there.

And if the starter is dead:

DQ Volume 5 Issue 4 - DIY Starter Rebuild - Tired of lifetime warranty starters that fail once a year? Don’t want to pay a mechanic $50/hour or more to rebuild yours? If you’ve got a Saturday afternoon available it’s much cheaper to disassemble/inspect and replace the worn parts yourself!

Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

I should also say that beyond getting the car started sooner than later I would like to clean up the engine bay wiring as much as possible. Is there a list somewhere of what relays/transistors/wiring can be removed and under what circumstances?

The headlight and front side marker wiring are a mess right now and I would also like to upgrade to H4 hi/low lights and amber fog lights so I plan on doing any necessary Harness changes to tidy that up.

Not a lot that can be removed, really. Mostly it involves the third-gear switch and relay on a dual-points car (if you have a translucent box over the throttle linkage at the firewall, you have this). Most everything else you're going to want for a street car.

H4 conversion is most easily done with an aftermarket relayed harness. Stock 510 wiring routes all headlight power through the headlight switch, so higher power lights end up burning out the switch. Datsun did incorporate a headlight relay into the system, but the circuit flow remains an issue. Using the stock system to trip an aftermarket relay is the way to go.

Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

Thanks for the help Julian. I have to admit I do look at wiring as a bit off black magic. I need to get over that. I have DQ V5 I3 printed out so I will read up on that article and I will print out the other issue you mentioned.That's good to know about the aftermarket harness for the H4 conversions, I will read up on that.

Also thanks for the tip on jumping the starter, you truly do learn something new every day. So I jumped it and it and thankfully it started turning over which is progress. Any ideas where to look next to figure out why the ignition isn't powering the starter?

In the meantime I will start hooking up the gas tank and any missing gas lines, or jury rig a temp fuel supply to see if I can get it to fire.

So I hooked up gas and gas is getting to the carb but it still isn't starting. Since it has ags and fuel but doesnt even seem to be igniting i'm assuming its spark. Any ideas anyone? I will keep researching and troubleshooting in the mean time.

The reserve tank of which you speak (if its in the trunk) is an evap tank - and you need it. Yes fuel line comes up on the pass side near the front signal light.
As far as starting - could be a starter solenoid - but you didn't mention how you go the engine running (how did you engage the starter?).

Since the engine will run when the ignition is ON and you jump the starter, you could have a couple issues. A short in the starter wire, a bad ignition switch, etc. With your diagram, look for which pins on the ignition plug need to be connected for engine START. Jump these pins at the connector (back of ignition switch, should be a 6-pin connector with 5 pins used).

Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

Should you get to that point and not find an issue, the next most likely cause is a wonky dogbone. To check that, pull the ignition switch assembly, then remove the switch itself from the lock cylinder. With the switch connected to the harness, use a screwdriver to turn the switch all the way to START. If it starts right up, then the metal dogbone that sticks out the back of the lock cylinder has been tweeked enough that it won't fully rotate the switch to START. Tweek it the other way to fix.

Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

it was an oversight on my part. The previous owner didn't have one of the wires connected to the starter solenoid. Now i need to get a set of keys and see if it will start from the ignition instead of a screwdriver from the switch.